1. Field of the Invention
The present invention relates to a non-rectangular pixel array and a non-rectangular display device made up of the pixel array and more particularly to the pixel array having a non-rectangular outer circumferential shape and the non-rectangular display device made up of the pixel array with outer circumferential portion of which has a shape of a smoothly curved line.
2. Description of the Related Art
In recent years, due to extension of applications associated with progress of miniaturization, thinning, light-weighting of a display device, demands for commercialization of such a display device made up of a pixel array (hereinafter, may be referred to as a display area) having a non-rectangular outer shape are increasing. Display devices of this kind are disclosed, for example, in Patent References 1 and 2 (Japanese Patent Application Publication Nos. 2005-528644 and 2005-529368, respectively). FIG. 45 shows configurations of the display device stated in the Patent Reference 1. The display device, as shown in FIG. 45, is mainly made up of a pixel array 40 having a non-rectangular outer shape, row driver circuits 41, 41, . . . divided into at least three portions, and column driver circuits 42, 42, . . . divided into at least three portions. The row driver circuits 41, 41, . . . and the column driver circuits 42, 42, . . . are alternately arranged along the circumference of the pixel array 40, and each pixel is addressed by the row driver circuits 41, 41, . . . and column driver circuits 42, 42, . . . each connected to a corresponding row conductor line and a corresponding column conductor line. By configuring as above, control for display/non-display even on the pixel array 40 forming a complicated outer shape can be exerted. However, in the Patent Reference 1, a shape of each pixel making up the pixel array is not described clearly. In the display device shown in the Patent Reference 1, as shown in FIG. 45, the row conductor line and column conductor line are alternately arranged in an orthogonal manner and, therefore, it is natural to assume that each pixel has a rectangular shape. (though a pixel electrode itself is not always rectangular, it is thought that, at least, a minimum pattern making up one pixel unit is rectangular).
According to the technology disclosed in the Patent Reference 1, a position of a shift point to be set on an outer circumferential portion having odd shapes of the pixel array 40, between the row driver circuit 41 and column driver circuit 42, which are adjacent to each other, is specified as follows. First, contact positions 43, 43, . . . (shown as black circles in FIG. 45) on an outer circumference where a tangent line to an outer circumferential portion having an odd shape of the pixel array is parallel to the row conductor line or column conductor line, are checked and these contact positions 43, 43, . . . are specified as the positions of the shift points. These contact positions 43, 43, . . . exist on an extruded portion on the outer circumference or at the most backward portion of a convex portion on the outer circumference. Next, if positions on the outer circumference positioned opposite, along the row line or column line, to these contact positions 43, 43, . . . are not specified yet as set positions of the shift points, these points are specified as positions 44, 44, . . . (shown as white circles in FIG. 45) of the shift points. When the row driver circuits 41, 41, . . . divided into a plurality of portions and the column driver circuits 42, 42, . . . divided into a plurality of portions are arranged according to the specification of all shift points, in a given pixel making up the pixel array 40, one end of the row contactor line is connected to the row driver circuit 41 and another end of the column contactor line is positioned in a manner to straightly face the column driver circuit 42. Similarly, in a given pixel, one end of the corresponding column contact line is connected to the column driver circuits 42 and another end of the column contactor line is positioned in a manner to face straightly the column driver circuit 42. Moreover, the display device is so configured that a carry signal is transmitted to a next column driver circuit 42 at an end of the divided column driver 42.
FIG. 46 shows a display device disclosed in the Patent Reference 2. The display device, as shown in FIG. 46, is made up of an octagonal pixel array 48 having a plurality of pixels 47, 47, . . . in which row pixels 45, 45, . . . intersecting at right angles and column pixels 46, 46, . . . are arranged. The row driver circuits 52 and column driver circuits 53, as shown in FIG. 46, are mounted at a highest corner on an outer circumference of the octagonal pixel array 48. Each of the pixels 47, 47, . . . making up the pixel array 48, as shown in FIG. 46, has a rectangular shape and is associated, in a one-to-one relationship, with each of intersections 51, 51, . . . of the first address designating conductors 49, 49, . . . and the second address designating conductors 50, 50, . . . making up a lattice, as a whole, and is uniquely addressed by one pair of the first address designating conductors 49 and second address designating conductors 50.
In display device, as shown in FIG. 46, the first address designating conductors 49, 49, . . . and the second address designating conductors 50, 50, . . . are arranged slantingly relative to the row and column of the rectangular pixels 47, 47, . . . and in a manner to be intersected diagonally with one another. By configuring as above, the row and column of the rectangular pixels 47, 47, . . . can be separated from the first address designating conductors 49, 49, . . . and the second address designating conductors 50, 50, . . . which enables freedom of position setting of the drive circuits to be obtained. Owing to the freedom, space can be saved so that conditions for product designing are satisfied. For example, as shown in FIG. 46, side space required on each side of a display area (pixel array 48) can be reduced, which enables a display area occupying region to be sufficiently increased and good centering to be achieved.
In the non-rectangular display device, it is desirous that the circumferential contour of the display area (pixel array) has a smooth and gentle shape (for example, closed curve). However, as described above, the conventional display devices stated in the Patent References 1 and 2 have disadvantages that, though the display area (pixel arrays 40 and 48) is non-rectangular, each rectangular pixel 47 making up the display area is rectangular and, therefore, a region occurs in which no matching between the rectangular pixel 47 and non-rectangular outer circumferential contour is realized. That is, in the configurations of the conventional display device, as shown in FIGS. 47 and 48, in the curved region (or slanted region) 54 out of the outer circumferential portions, a plurality of pixels 47, 47, . . . is arranged in a stepwise manner and, as a result, the display area having a smooth and gentle contour shape cannot be obtained, which gives uncomfortable jaggies to viewers, causing a loss of attractive appearance and unfavorable designing.
Also, the display devices disclosed in the Patent References 1 and 2 have another problem in that, when a given slant line or curved pattern including an outer circumferential contour of a shape is to be displayed, more specifically, an equal distance line pattern (due to mimicking of a contour line on a map, such a pattern is referenced to as a contour line like shape or figure) obtained by performing linking between positions, by a specific equal distance, far from a pattern similar to an outer circumference of a display area or from an outer circumferential contour or the like is to be displayed, since a plurality of rectangular pixels is selected and controlled in a stepwise manner, as shown in FIG. 48, a slant figure or curved FIG. 55a is visually recognized by a viewer as the pattern having uncomfortable jaggies and distortion, which is not preferable in terms of display quality.
In addition, the color display device having the rectangular display area (in the example, display area having the same as in FIG. 48) shown in FIG. 49 also has a problem in that a region occurs in which a specified color only is enhanced in an outer circumferential curved portion of a display area or in an outer shape line portion of a display pattern, which is recognized as irregular color or a like. In the color display device, each pixel 57, as shown in FIG. 49, is made up of three kinds of color pixels (color segment) including a rectangular red pixel (red segment) 57r having a red color filter, a rectangular green pixel (green segment) 57g having a green color filter, and a rectangular blue pixel (blue segment) 57b having a blue color filter, and is configured to form a rectangular pixel unit. The color pixels of three kinds are formed in a stripe form, as a whole.
In the color display device, when a contour line like shape 55 being similar to an outer circumferential contour of a display area is displayed in white with the priority being given to its shape, as shown in FIG. 49, the pixel region appears in which only the green pixel 57g and blue pixel 57b are displayed and no red pixel is displayed (regions indicated by circular marks in FIG. 49). In the pixel region corresponding to an outer shape curved portion of a display pattern, no white is observed sporadically and cyan (jagged color spreading) obtained by mixing blue and green is observed, which is not preferable in terms of display quality. In order to solve this problem, white is displayed by necessarily using the red pixel 57r, green pixel 57g, and blue pixel 57b making up the pixel 57 (that is, with the priority given to a hue). However, a problem arises that, by displaying in white with the priority given to a hue, irregular colors disappear, while a corner occurs in three color pixels and jaggies increase in the display area and display pattern which, in this case, are uncomfortable.
In addition, another problem arises that, the display device having an extremely odd shape in which a hollow portion or through hole exists in the display area, out of the non-rectangular display devices, can not be realized by configurations disclosed in the Patent References 1 and 2.
Further, the display device stated in the Patent Reference 2 also has a disadvantage in that, as shown in FIG. 46, each of the first address designating conductors 49, 49, . . . and each of the second address designating conductors 50, 50, . . . pass slantingly through an aperture of each of the rectangular pixels 47, 47, . . . resulting in partial blocking of the aperture, thus causing a decrease in an aperture rate. The display device still further has a disadvantage that the positions in which the first address designating conductors 49, 49, . . . and second address designating conductors 50, 50, . . . intersect with each other in the rectangular pixels 47, 47, . . . differ for every rectangular pixel 47 and, as a result, an arrangement of the switching elements mounted in a one to one relationship at the intersection region or its vicinity area differ for every rectangular pixel 47, which makes designing of the display device be extremely difficult. As is described above, the arrangement of the switching elements is not equal and, therefore, the places where a failure or the like occurs are different, which makes the inspection to be complicated and makes it difficult to manufacture the display device having an equal quality.
The display device stated in the Patent Reference 2 has another disadvantage that the rectangular pixels 47, 47, . . . , first address designating conductors 49, 49, . . . , and second address designating conductors 50, 50, . . . arranged in directions being different from one another at pitches different from one another and, therefore, a moiré (coarse interference fringe) of this kind occurring structurally appears principally by overlapping of a design changing regularly and the moiré cannot be deleted by a simple means which is troublesome. By adjusting the shape of the rectangular pixels 47, 47, . . . , and the angle at which first address designating conductors 49, 49, . . . and second address designating conductors 50, 50, . . . intersect with one another, this kind of moiré can be reduced, however, the angle adjustment causes a decrease in an aperture ratio and the angle adjustment is accompanied by large designing constraints, for example, designing problems that the arrangement position of peripheral circuits interfere with the shape of the display area.
In the display device disclosed in the Patent Reference 2, it is possible to perform a conformal mapping method on the rectangular pixel array, thus obtaining a non-rectangular pixel array in which jaggies can be reduced. However, this display device has a disadvantage that regularity of each pixel is decreased and a symmetric property is degraded, which causes lowered viewability of a displayed pattern, in particular, of characters. In the pixel array obtained by the conformal mapping method, no repetition of a minimum pattern occurs in many cases and manual designing of each pixel based on calculated coordinates is required, causing extremely complicated work to be unavoidable. Moreover, even after the completion of designing, there are little simple repeated patterns, which extremely increases data amounts and work and the number of man-hours in mask processing thereafter, which is not preferable in terms of actual usability.
Further, in the non-rectangular display device disclosed in the Patent References 1 and 2, it is not assumed that a potential or signal is supplied to a corresponding electrode of each pixel and third conductor line group used to change the supplied potential or signal is mounted. If the third conductor line group is added to the configuration stated in the Patent Reference 1, due to a small space region in the vicinity of the outer circumferential portion of the pixel array 40, it is necessary that a third driver circuit is mounted outside two kinds of driver circuits 41 and 42 already mounted, thus increasing a ratio of a peripheral circuit region to the pixel array 40, which is not preferable to achieve a non-rectangular display device attaching importance to a design result. In addition, many intersection regions occur among conductor lines to be connected to the driver circuits 41 and 42, driver circuits 41 and 42, third conductor line, which causes a disadvantage that cross capacitance generated by overlapping of conductor lines and parasitic capacitance generated by approach between a conductor line or driver circuit and another conductor increase. In order to suppress an influence exerted on the increased parasitic capacitance, it is assumed that load capacitance may occur in the driving circuit, however, this method is accompanied by an increase in a circuit area. Moreover, the driver circuit and conductor lines are arranged in a complicated manner and, therefore, the fear of the occurrence of a short circuit between the conductor line and circuit arises, which reduces a production yield and reliability.
In the configuration stated in the Patent Reference 2, it is possible that the third peripheral circuit (not shown) can be easily mounted in a place where the driver circuits 41 and 42 do not overlap and, for example, may be mounted on a lower side of the display area in FIG. 46. However, in the configuration stated in the Reference 2, as described above, the position where the row conductor line and column conductor line intersect with each other differs for every pixel, thus possibly causing further difficult designing and increase in the occurrence of moiré.
Moreover, in Patent Reference 3 (Japanese Patent Application Laid-open No. 2004-212498), Patent Reference 4 (Japanese Patent Application Laid-open No. 2004-212500), and Patent Reference 5 (Japanese Patent Application Laid-open No. 2006-276359), technologies for the non-rectangular display device are described, however, no description of each problem of the above-described conventional technologies and technological method to solve the above problems is provided.